Project Summary/Abstract Glioblastoma (GBM) remains a fatal brain cancer for which there is no cure. Maximal safe tumor resection combined with adjuvant therapies such as fractionated external beam radiation therapy (RT) and temozolomide (TMZ) chemotherapy, known as chemoradiation (CRT), has provided the greatest benefit to GBM patients. However, local recurrence occurs in most patients due to invasive therapy-resistant infiltrating cancer cells at the tumor margin. Magnetic hyperthermia therapy (MHT) is a powerful nanotechnology-based treatment that may enhance the effects of CRT. MHT consists of local heat generation in the tumor region through direct delivery of magnetic iron-oxide nanoparticles (MIONPs) that are activated by exposure to an external alternating magnetic field (AMF) that is safe to normal cells. The AMF interacts with the magnetic dipoles of the MIONPs to generate local heat and hyperthermia. Human clinical trials have demonstrated overall survival benefits of MHT with fractionated RT in recurrent GBM resulting in European approval. Current MHT strategies, however, require high concentrations of nontargeted MIONPs (>100 mg/ml; 50-100mg Fe/g of tumor) delivered by injection with leakback and without image-guided control of energy deposition. As a result, normal tissue injury limits MHT effectiveness and treatment of the infiltrative tumor margins is poorly defined, which compromises MHT efficacy. Our proposal is designed to address these challenges and optimize the translational potential for enhanced MHT of GBM in combination with CRT using both small and large animal models, with clinical proof-of-concept demonstration in spontaneous canine gliomas. We have recently completed a pilot study in spontaneous canine gliomas demonstrating feasibility and safety of image-guided MIONP delivery alone. We hypothesize that image-guided MHT will enhance CRT of GBM. Key innovations of our proposal are to: 1) evaluate the enhancement of CRT by MHT in mouse GBM models with an innovative proprietary MIONP formulation that requires 20-fold lower Fe concentration in tumors for more effective treatment than current approved MIONPs; 2) optimize image-guided MIONP delivery and MHT treatment planning with computational modelling in a rabbit brain tumor model; 3) enhance thermal treatment at the infiltrative tumor margins by controlling power deposition with innovative AMF power application that will also limit off target heating; and, 4) complete a clinically relevant proof-of-concept study of our MHT approach in a spontaneous canine glioma model. We have Preliminary Data that demonstrate intracranial hyperthermia with a 3-fold increase in TMZ concentration within GBM tumors, leading to a robust antitumor effect with increased survival after MHT + CRT in a therapy-resistant rodent glioma model. Overall, this interdisciplinary work will provide a solid foundation for meaningful clinical translation of MHT with CRT for treatment of GBM. Imaging methods that correlate tumor heat distribution after MHT will be developed for translation to human patients.